Caulking For Fiber Cement Siding

1 i chose this caulk because it has 25 flexibility compared to silicone based caulk.

Caulking for fiber cement siding.

Do not caulk fiber cement butt joints edges. Fiber cement boards don t expand and contract much but leave a little room for expansion at the end joints and then fill the gap with caulk. Caulk is usually used with fiber cement siding to prevent water intrusion at the butt joints. The specification to omit caulk at siding butt joints is for new installations and is discussed in detail by the manufacturer.

When james hardie siding products butt into wood based materials a 1 8 gap will allow for expansion and contraction of the wood based product. Applying caulk to the butt joint is ineffective because the gap is not large enough to accommodate the sealant. Some manufacturers do not require the metal flashing therefore we caulk the butt joint to keep the pieces together and also prevent moisture. Trim boards wood windows.

Caulking around windows doors eaves and trim edges gives added insurance that leaks will not occur. Butt joints however should be nailed tightly together and should not be caulked. So what i would tell you to do is to use a colored caulk to choose the caulk in the color of the siding. We only caulk butt joints on cedar siding if previously caulked.

Many professionals like those at james hardie also agree that you should not use caulk on fiber cement siding unless there is no metal flashing underneath. Item 157140 model 11532. However this detail may not be effective at sealing the ends allowing water to be absorbed and swell the board ends. Fiber cement boards are caulked only when there is no metal flashing behind them.

Dap alex plus 12 pack 10 1 oz white paintable latex caulk.